The cluster birthline in M 33

O-33: Serum Anti-M

The Ofpe/wn9 Stars in M 33

We present HST/STIS Ultraviolet spectra of the six known Ofpe/WN9 stars (“slash stars”) in M 33. These stars were selected for showing the characteristics of the Ofpe/WN9 class from previous optical ground-based spectroscopy. The UV spectra are rich in wind lines, whose strength and terminal velocity vary greatly among our target sample. We analyse the STIS spectra with non-LTE, line blanketed,...

The Angular Momentum Evolution of 0.1-10 M⊙ Stars from the Birthline to the Main Sequence

Projected rotational velocities (vsini) have been measured for a sample of 145 stars with masses between 0.4 and >10 M⊙ (median mass 2.1 M⊙) located in the Orion star-forming complex. These measurements have been supplemented with data from the literature for Orion stars with masses as low as 0.1 M⊙. The primary finding from analysis of these data is that the upper envelope of the observed valu...

Observations of the Nucleus of M 33

The nearby galaxy M33 hosts the most luminous steady X-ray source in the Local Group. The high spatial resolution of Chandra allows us to confirm that this ultra-luminous X-ray source is within the nucleus and rule out at the 4.6σ level a previously proposed possible counterpart located 1 away. The X-ray spectrum is well fitted by a disc blackbody with kTin=1.18±0.02 keV and Rin(cos θ)=57±3 km,...

The Compact Uv Nucleus of M 33

The most luminous X-ray source in the Local Group is associated with the nucleus of M33. This source, M33 X-8, appears modulated by ∼ 20% over a ∼ 106 day period, making it unlikely that the combined emission from unresolved sources could explain the otherwise persistent ∼10erg s X-ray flux (Dubus et al. 1997, Hernquist et al. 1991). We present here high resolution UV imaging of the nucleus wit...